Gear for John Muir Trail next week

I have never camped up that high during this time of year, but I think you should be expecting lows in the 20s or teens (someone correct me if I'm wrong).

Where specifically?

Guitar Lake Forecast

Scroll around on the Forecast Map, then click the spot of your choosing.
Bookmark that, and watch it for the next week.

"Scroll around on the Forecast Map, then click the spot of your choosing.
Bookmark that, and watch it for the next week."

+1 And be aware that the weather forecasts are not 100% accurate. Keep checking up until the last minute, and be prepared to cancel if things start to look iffy. Once you're back in there, a sudden storm could strand you, so keep an eye on the western horizon, keep track of falling barometric pressure if you have an altimeter/barometer, and always be thinking of the nearest East Side pass you can bail out over if the weather turns bad. Also, as Justin said, be prepared for potential weather at least into the low 20's, and take enough food to last for a couple extra days, on the off chance you do get snowed in and have to go to ground until the storm passes. People have died up there by ignoring these basic precautions. That said, here's to good weather and a great trip.

These are great wx sites. I'm thinking in launching from Reds Meadow area. Looks like it might be a few degrees colder than I thought it may be. I've been in the area before. Darn I wish it stayed warm for longer but this will allow me to test some new warmer gear. Cheers.

I've done a trip to the top of Mt Brewer on the last weekend of Oct.

It was a very warm weekend and saw zero people the entire trip.
First night at 10,800' was 25F and second night on top at 13,600' was 13F.

I'm seeing 30F on NOAA Weather but if a cold snap comes through (which do almost always durning this time of the year), it will drop another 10F below the predicted temps.
It will get much much colder than 40F. I would expect 25F and be ready for 15F.

I don't think your original forecast is correct… those were the temperatures we had on the JMT in August at the lower elevations!

Even though it's "indian summer", I think the highs will be in the 50Fs, and the lows will be below 30F, and maybe 20F, even if you camp lower. No problem while you're hiking, but bring a nice toasty-warm sleeping bag/pad.

Go to Mesonet http://www.wrh.noaa.gov/mesowest/gmap.php?map=vef and you can look up the actual temps that have been occurring within the area you want to hike. I'd say the current temps are much lower that what you posted.

After Labor Day, I always plan on lows around 20F (for both camping and hiking). For October, I'd plan for the teens. I've seen 20F in Tuolumne Meadows in mid September when it snowed. For 2-3 day trips, you can usually trust the forecast if you have one from the right place that accounts for the elevation. But out any longer, you have to assume that the weather can change for the worse from what was forecasted. October weather is much more unstable and unpredictable in my experience then summer.

I did the Tahoe Yosemite Trail back in late September which ranges between 5,000 and 10,000 ft and saw night time temps between the low 30's and mid 40's and daytime temps between the low 40's to the high 70's. The daytime low in the 40's happened after a thunderstorm dumped a few inches of hail on me in the Emigrant Wilderness and the temperature dropped by 30F. It never did warm back up afterwards since the clouds never left and the rain kept coming back over the rest of the afternoon and evening. You are going out a month later when the high country is already past fall.